Coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle



United States Patent [72] Inventor [21] Appl. No.

[22] Filed [45 Patented [73] Assignee [54] COATED STOPPER HEAD FOR CONTROLLING OUTFLOW OF MOLTEN METAL THROUGH THE NOZZLE OF A BOTTOM POUR RECEPTACLE I 4 Claims, No Drawings [52] US. 251/356 [51] IIILCI Fl6lt 21/00 [50] Field ofSearch 251/291,

, 356; llS/(lnquired); 164/73; 222/544, 559;

3,192,582 7/1965 Cope et al 222/559 3,196,504 7/1965 Limes ll7/5.3X 3,389,006 6/1968 Kohler..... 117/1 27X 3,428,464 2/1969 Pollard ll7/5.3X 3,429,486 2/1969 Cope et al 222/559 Primary Examiner-Samuel Scott Attorney-Edward Hoopes, Ill

ABSTRACT: A coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle comprising a stopper head body with an insulating coating thereon so that when the stopper head is in position closing the nozzle and molten metal is introduced into contact with the relatively cold stopper head the insulating coating on the stopper head minimizes cooling of the molten metal in the vicinity of the stopper head and hence inhibits freezing of mo]- ten metal to the stopper head so that when the stopper head is subsequently urged upward to permit outflow of molten metal through the nozzle raising of the stopper head will not be substantially impeded by metal frozen thereto. The coating preferably comprises finely divided insulating material and a binder and is desirably of such consistency that it may be applied by dipping. The insulating material is preferably in unfired finely divided form. The coating is preferably formed in situ on the stopper head body.

COATED STOPPER HEAD FOR CONTROLLING OUTFLOW OF MOLTEN METAL THROUGH THE NOZZLE OF A BOTTOM POUR RECEPTACLE This invention relates to a coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle. While the invention is of wide application it has especial utility in stopper heads for bottom pour receptacles for pouring or teeming molten metal such as bottom pour ladles'and tundishes used for pouring or teeming molten steel either into ingot molds or into continuous casting apparatus.

For purposes of explanation and illustration the invention will be described as applied to a stopper head for a bottom pour molten steel ladle or tundish. When molten steel at a temperature of the order of 2900" F. is introduced into a receptacle such as a ladle or tundish having a nozzle in its bottom which is initially closed by a relatively cold stopper head (see, for example, U.S. Pat. No. 3,352,535) the great difference in temperature between the incoming molten steel on the one hand and the stopper head on the other hand is so great that some of the molten steel freezes to the stopper head. This is a phenomenon well known to those skilled in theart which has existed since the inception of the use of bottom pour receptacles for handling molten steel. The steel frozen to the stopper head renders difficult or impossible the raising of the stopper head to permit outflow of molten steel through the nozzle in the bottom of the receptacle. The result is damage to the stopper head in any effort'to free itfrom the frozen steel which in turn makes impossible optimum control of outflow of steel from the receptacle and in many cases results in inability to shut off the flow at all once the stopper head is unseated.

Various efforts have been made to solve the problem. For

. example, materials such as sand or lead have been introduced around the stopper head at the upper portion of the nozzle in an attempt to provide a temporary barrier between the stopper head and the initial increment of molten steel entering the receptacle. Such procedures are difficult and cumbersome due to the temperature of a preheated receptacle which may be of the order of several hundred degrees Fahrenheit. Moreover they have not satisfactorily prevented the molten steel from freezing against the stopper head, and the introduction of such foreign materials is detrimental to the quality of the steel.

l have solved the problem by providing a coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle comprising a stopper head body with an insulating coating thereon so that when the stopper head is in position closing the nozzle and molten metal is introduced into contact with the relatively cold stopper head insulating coating on the stopper head minimizes cooling of the molten metal in the vicinity of the stopper head and hence inhibits freezing of molten metal to the stopper head so that when the stopper head is subsequently urged upward to permit outflow of molten metal through the nozzle raising of the stopper head will not be substantially impeded by metal frozen thereto. The coating preferably comprises finely divided insulating material and a binder and is desirably of such consistency that it may be applied by dipping. The insulating material is preferably in unfired finely divided form. The coating' is preferably formed in situ on the stopper head body.

The coating on the stopper head acts in the nature of a thermal barrier. The insulating material is desirably in finely divided or powdered form and may comprise various compositions; examples are dolomite, magnesite, bloated clay, refractory impregnated paper, plastics (ablation type), exothermic materials, amorphous carbon and pyrolytic graphite. Such material is mixed with a binder to form a slurry, mortar, dip coat or wash. The binder may be of various compositions; examples are dextrose, gulac, starch and phosphoric acid. As above stated, the coating is preferably of such consistency that it may be applied by dipping, or it may be applied by brushing or spraying. The thickness of the coating may be of the order of one-fourth inch, more or less.

While I have described certain present preferred embodiembodied within the scope of the following claims.

lclaim:

l. A coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle comprising a stopper head body with an insulating coating thereon so that when the stopper head is in position closing the nozzle and molten metal is introduced into contact with the relatively cold stopper head the insulating coating on the stopper head minimizes cooling of the molten metal in the vicinity of the stopper head and hence inhibits freezing of molten metal to the stopper head so that when the stopper head is subsequently urged upward to permit outflow of molten metal through the nozzle raising of the stopper head will not be substantially impeded by metal frozen thereto.

2. A coated stopper head for controlling outflow of molten metal through the noule of a' bottom. pour receptacle as claimed in claim 1 in which the. coating comprises finely divided insulating material and a binder and is of such consistency that it may be applied by dipping.

3. A coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle as claimed in claim 1 in which the coating comprises unfired finely divided insulating material.

4. A coated stopper head for controlling outflow of molten metal through the nozzle of a bottom pour receptacle as claimed in claim 1 in which the coating is formed in situ on the stopper head body.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,549,124 Dated December 22 1970 Inventofls) RONALD V. KILGORE It is certified that error appears 1p the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 19, "3,352,535" should be 3,352,534; line 52, after "head" insert the-.

Ame:

H. JR Awning 015w! Winona!- at Patlnts 

